If you follow up a bit more on John Nolan, the nailer who was in Belfast city directories in the 1870s, you should be able to identify his wife and learn if he's the right man (of whatever religious persuasion). He was a widower by 1901, living on Alexander Street, see the census extract below.
1901 census of Ireland - Residents of a house 14 in Alexander Street (St. Anne's Ward, Antrim):
John Nolan - 60 - Head of Family - R Catholic - born Co Down- Retired Nail Maker - Cannot read - Widower
John Nolan - 40 - Son - R Catholic - born Belfast - Nail Maker - Cannot read - Married
Cathrine Nolan - 30 - Daughter in Law - R Catholic - Belfast - Charwoman - Read only - Married
Hannah Nolan - 21- Daughter - R Catholic - Belfast - Spinner in Linen Mill - Read only - Not Married
In 1911, I see the son John and his wife Catherine at another address in Belfast. He's still a nailer, as his father was. And, as I said in a previous message, I think the John Nolan who died in 1906 was the head of family of the 1901 census, a retired nailer.
A search for John Sr.'s daughter Hannah (age 21 in 1901, born Belfast, so born about 1880) in civil birth registrations might confirm or refute that this family was John Nolan and Jane Jewell. She might have been Hannah Jane or another name combination (like everyone else you're searching for), and remember that Ann & Anna & Annie are used for Hannah. "Jane Jewell" might have been a "Hannah Jane" or similar name.
Other Belfast records that you can search are city-generated, such as the burial records.
www.belfastcity.gov.uk/burialrecords includes:
Belfast City Cemetery - records from 1869
Roselawn Cemetery - records from 1954
Dundonald Cemetery - records from 1905
However, church cemeteries aren't included in this city burials database, nor is Shankill Graveyard -- one of the oldest cemeteries in Belfast.
History from Headstones has inscriptions from at least one Shankill parish graveyard that includes a NOLAN (via the "Free Search"):
www.historyfromheadstones.comOn the Co. Antrim site of IFHF, there's ONE match for a NOLAN child born to parents John & Jane Nolan in Co. Antrim. I'd certainly order that record, if I was you, to see who it was and if it's the right family. An instantly downloadable transcript is only a few euros, well worth the research effort.
If you do find that this IFHF birth record has the right parents, write me a personal message and I'll see if I can help you further. Also there's a marriage of Hannah Nolan, daughter of John Nolan, between 1901 & 1909... perhaps the daughter of John the nailer of the 1901 census and 1870s city directories? Order the record and see! Also there are 11 marriages of all Nolans with father named John in Belfast between 1885 and 1905. Some might be your Mary Kathleen's siblings.
Annie